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Method for improving thickness precision of ultrahigh-strength cold-rolled dual-phase steel

A thickness precision, dual-phase steel technology, applied in furnace types, furnaces, heat treatment furnaces, etc., can solve problems such as failure to meet use requirements and hinder product promotion and application.

Active Publication Date: 2021-07-13
PANGANG GRP XICHANG STEEL & VANADIUM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the dual-phase steel whose thickness changes periodically after cold rolling cannot meet the requirements of use, which seriously hinders the promotion and application of this series of products.

Method used

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  • Method for improving thickness precision of ultrahigh-strength cold-rolled dual-phase steel
  • Method for improving thickness precision of ultrahigh-strength cold-rolled dual-phase steel
  • Method for improving thickness precision of ultrahigh-strength cold-rolled dual-phase steel

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Production variety: 780DP

[0038] Hot rolling thickness: 4.0mm

[0039] Cold rolling thickness: 1.79mm

[0040] Slab length: 10m

[0041] Laminar flow cooling: air cooling in the front section, water cooling in the back section, the starting temperature is 720-740°C, and the water cooling rate is ≥80°C / s

[0042] Coiling temperature: 550-570°C

[0043] The thickness curve of cold rolling is shown in the appendix figure 1 .

Embodiment 2

[0045] Production variety: 980DP

[0046] Hot rolling thickness: 3.25mm

[0047]Cold rolling thickness: 1.79mm

[0048] Slab length: 10m

[0049] Laminar flow cooling: air cooling in the front section, water cooling in the back section, the starting temperature is 700-720°C, and the water cooling rate is ≥50°C / s

[0050] Coiling temperature: 580-600°C

[0051] The thickness curve of cold rolling is shown in the appendix figure 2 .

Embodiment 3

[0053] Production variety: 1180DP

[0054] Hot rolling thickness: 2.3mm

[0055] Cold rolling thickness: 1.39mm

[0056] Slab length: 10m

[0057] Laminar flow cooling: air cooling in the front section, water cooling in the back section, the starting temperature is 680-700°C, and the water cooling rate is ≥50°C / s

[0058] Coiling temperature: 580-600°C

[0059] The thickness curve of cold rolling is shown in the appendix image 3 .

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Abstract

The invention discloses a method for improving the thickness precision of ultra-high-strength cold-rolled dual-phase steel. A laminar cooling process adopts front-section air cooling and rear-section water cooling, and the water cooling starting temperature is greater than or equal to the phase change starting temperature of proeutectoid ferrite; and the coiling temperature in the coiling step is less than or equal to the transformation end temperature of the proeutectoid ferrite. By the adoption of the method, phase change of the proeutectoid ferrite can be achieved at the high cooling speed, the amount of transformation of carbon in the ferrite to super-cooled austenite is greatly reduced, the hardenability of the super-cooled austenite is reduced, and therefore stress-induced phase change after coiling is reduced, and the thickness precision of the cold-rolled dual-phase steel is improved; and meanwhile, the grain size of austenite is increased through front-section air cooling, the yield strength of hot-rolled strip steel is reduced, part of increment generated by water cooling of rear-section proeutectoid ferrite area can be offset, and therefore the rolling passing rate of cold rolling is increased.

Description

technical field [0001] The invention relates to the technical field of ultra-high-strength cold-rolled dual-phase steel, and more specifically relates to a method for improving the thickness accuracy of ultra-high-strength cold-rolled dual-phase steel. Background technique [0002] Ultra-high-strength cold-rolled dual-phase steel, such as 780MPa-grade cold-rolled dual-phase steel, as a typical steel grade of the first generation of advanced high-strength automotive steel, is widely used in automotive structural parts and reinforcements, which can reduce the weight of raw materials by more than 30% , and significantly improve the safety of the car. [0003] However, ultra-high-strength cold-rolled dual-phase steel has high alloy content, complex phase transformation process, and poor microstructure uniformity after hot rolling, resulting in periodic fluctuations in thickness after cold rolling. The periodic fluctuation of cold-rolled thickness is due to the phase transformat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D6/00C21D11/00C21D9/00B21C47/02
CPCC21D6/00C21D11/005C21D9/0081B21C47/02C21D2211/005C21D2261/00
Inventor 唐梦霞周三保陈俊张龙超田维兵王羿龚慧唐超
Owner PANGANG GRP XICHANG STEEL & VANADIUM CO LTD